Redox amplification processes have been described, for example in British Specifications Nos. 1,268,126; 1,399,481; 1,403,418; and 1,560,572. In such processes, color materials are developed to produce a silver image (which may contain only small amounts of silver) and treated with a redox amplifying solution (or a combined developer/amplifier) to form a dye image.
The developer/amplifier solution generally contains a color developing agent and an oxidizing agent which will oxidize the color developing agent in the presence of the silver image which acts as a catalyst.
Oxidized color developer reacts with a color coupler to form the dye image. The amount of dye formed depends on the time of treatment or the availability of the color coupler and is less dependent on the amount of silver in the image than is the case in conventional color development processes.
Examples of suitable oxidizing agents include peroxy compounds including hydrogen peroxide and compounds which provide hydrogen peroxide, e.g., addition compounds of hydrogen peroxide such as perborates and addition compounds of hydrogen peroxide with urea. Other oxidizing agents include cobalt (III) complexes including cobalt hexammine complexes; and periodates. Mixtures of such compounds can also be used.
Such redox amplification processes are designed for processing low silver color papers, for example, those having about 200 mg/m.sup.2 or less of silver and generally cannot be used to process conventional color papers that typically contain from 500 to 700 mg/M.sup.2 because gross overamplification would occur. If it is necessary to process both lower silver and conventional higher silver photographic recording materials in the same processing apparatus, it is currently not possible to avoid the expense and inconvenience of having to empty and recharge the processor with different processing solutions (specifically different developers).
The present invention provides a solution to these problems.